The Spectro XR<sup>TM</sup> is an advanced color/NIR/SWIR/MWIR 16’’ payload recently developed by Elbit Systems / ELOP.
The payload’s primary sensor is a spotter camera with common 7’’ aperture. The sensor suite includes also MWIR
zoom, EO zoom, laser designator or rangefinder, laser pointer / illuminator and laser spot tracker. Rigid structure,
vibration damping and 4-axes gimbals enable high level of line-of-sight stabilization. The payload’s list of features
include multi-target video tracker, precise boresight, strap-on IMU, embedded moving map, geodetic calculations suite,
and image fusion.
The paper describes main technical characteristics of the spotter camera. Visible-quality, all-metal front catadioptric
telescope maintains optical performance in wide range of environmental conditions. High-efficiency coatings separate
the incoming light into EO, SWIR and MWIR band channels. Both EO and SWIR bands have dual FOV and 3 spectral
filters each. Several variants of focal plane array formats are supported.<p> </p>
The common aperture design facilitates superior DRI performance in EO and SWIR, in comparison to the
conventionally configured payloads. Special spectral calibration and color correction extend the effective range of color
imaging. An advanced CMOS FPA and low F-number of the optics facilitate low light performance. SWIR band
provides further atmospheric penetration, as well as see-spot capability at especially long ranges, due to asynchronous
pulse detection. MWIR band has good sharpness in the entire field-of-view and (with full HD FPA) delivers amount of
detail far exceeding one of VGA-equipped FLIRs.<p> </p>
The Spectro XR offers level of performance typically associated with larger and heavier payloads.
There is a growing need for dual band cameras in airborne reconnaissance systems having simultaneous operation in the 0.5-0.9 μm and 3-5 μm spectral bands. The dual band requirement stems from considerations of system performance and cost as well as installation on the platform. Airborne reconnaissance cameras require optical systems with long focal length and large apertures in the 3-5 mm wavelength IR region. A large optical system conflicts with the limitations of weight and volume often associated with long-range reconnaissance platforms. A dual-waveband airborne telescope and camera system has been developed by El-Op Ltd. This system provides high-resolution images in the thermal IR at night and simultaneous IR and visible images during day. It offers low weight, compact size and high dimensional stability over a wide range of environmental conditions. To enable the operation of the dual band, a unique dichroic beam splitter with special coating and broad band anti-reflection coating was developed for optimization of the transmittance in each band. The optical design of the telescope, the coating and its performance will be presented in the paper.
Cameras for remote sensing and for long range reconnaissance on airborne and space platforms in the 0.4-1.0 μm region exist, but there is a growing need for images in longer IR wavelengths. In those wavelength regions, large apertures are essential to achieve satisfactory ground resolution but this conflicts with the limitations of weight often associated with long-range reconnaissance platforms. The high costs of the system itself and of its installation on the platform make it advantageous to provide both wavelength bands in a single instrument. A dual-waveband airborne telescope and camera system has been developed by El-Op Ltd. which will provide high-resolution images in the thermal IR at night and in the visible in daylight, or both simultaneously. It offers low weight, compact size and high dimensional stability over a wide range of environmental conditions. The two detector arrays are mounted in a compact focal plane assembly with a spectral beam-splitting system that optimizes the transmittance of each band. A cooled IR detector is essential to achieve the necessary sensitivity and a special detector array with a high reliability, lightweight, low power cooling unit has been developed.
A new era in commercial remote sensing from satellites is beginning, with the emergence of high-resolution cameras that approach the capabilities of aerial photography. The first satellite of the EROS constellation will be launched in a few months and will provide panchromatic images of the Earth at a resolution of 1.8 m. Subsequent units will follow with one meter class panchromatic systems and 3.2 m multi-spectral channels. The constellation will allow high revisit rates and large data collection capacity over most of the Earth. The paper will describe the payloads planned for the series with emphasis on the technological features of the cameras.
Segmenting of the incident wavefront at the entrance pupil of an optical system, occurs in systems with segmented windows and in certain configurations of scanning systems that include polygons as the scanning element. Segmenting of the wavefront may cause a serious degradation to the MTF of the system. In some cases, the resolution of such systems may be decreased by a factor of two. In this paper, the degradation of the MTF is calculated for coherent and incoherent light. It is shown how such cases may be simulated using the CODE- V<SUP>R</SUP> software. An experimental setup was performed in order to demonstrate the incoherent case and its results are presented.
Segmenting of the incident wavefronts at the entrance pupil of an imaging system occurs in systems with segmented windows and in certain configurations of scanning systems that include a polygon as the scanning element. The segmenting of the wavefronts may cause a serious degradation of the MTF of the system. In some cases, the resolution of such systems may be decreased by a factor of two. The degradation of the MTF is calculated for monochromatic and polychromatic light. It is shown how such cases may be simulated using Code-V software.
An athermalized objective has been designed for a compact, lightweight push-broom camera which is under development at El-Op Ltd. for use in small remote-sensing satellites. The high performance objective has a fixed focus setting, but maintains focus passively over the full range of temperatures encountered in small satellites. The lens is an F/5.0, 320 mm focal length Tessar type, operating over the range 0.5 - 0.9 micrometers . It has a 16 degree(s) field of view and accommodates various state-of-the-art silicon detector arrays. The design and performance of the objective is described in this paper.
TAUVEX (Tel-Aviv Ultra Violet Explorer) is a telescope for the far UV spectral region. It will record images of the UV radiation from stars and other celestial sources from an orbiting satellite. The optical system consists of three identical and independent telescopes. The objectives of the system are based on a Ritchey-Chretien (RC) model with a field lens group to enlarge the field of view (FOV). These telescopes have been designed for the spectral region of 140 nm - 280 nm, and each has a spectral filter wheel to select a narrow spectral bandwidth. The use of different spectral bands for each telescope enables a multi spectral image to be recorded. This paper reviews the key optical design and fabrication points. The different available objective types for this program are described and analyzed to clarify the reasons for choosing the Ritchey-Chretien model.